Scan codes are the raw numbers sent by the keyboard. A PS/2 driver typically supports three scan code sets, but is the default. The driver must translate Set 2 to Set 1 (the original PC/XT codes) or directly to character codes.

Data is transmitted bit-by-bit over two lines: Clock and Data . Unlike USB, the keyboard itself generates the clock signal. Super Userhttps://superuser.com

A standard PS/2 keyboard driver is typically part of a system’s hardware abstraction layer (HAL) or a low-level input driver. Its main responsibilities include:

To truly appreciate the driver standard, you must understand the scan code set.

The standard PS/2 keyboard driver is a model of simplicity in device driver design. With only a few I/O ports, an interrupt handler, and scan code translation logic, it provides low-latency, reliable keyboard input. While USB dominates modern systems, the PS/2 driver remains an excellent learning tool for aspiring OS developers and continues to serve in specialized applications where timing predictability and minimal complexity are paramount.

Key electrical characteristics:

To understand the “driver standard” for a PS/2 keyboard, you must understand why Windows and Linux still ship with native support for this protocol decades after its supposed "death." This article dives deep into what the standard PS/2 driver does, why it outperforms USB in specific scenarios, and how to troubleshoot it on modern operating systems.

| Command (hex) | Description | |---------------|-------------| | 0xED | Set LEDs (Caps, Num, Scroll) | | 0xEE | Echo test | | 0xF3 | Set typematic rate/delay | | 0xF4 | Enable keyboard scanning | | 0xF5 | Disable keyboard scanning | | 0xFE | Resend last byte | | 0xFF | Reset keyboard |